NASA is celebrating its 50th birthday, and what a ride it has been! The space agency has sent humans to the moon and probes to the edge of the solar system, meeting with triumph as well as tragedy. Learn about 10 firsts from the space agency’s first 50 years.

Today NASA unveiled plans to return humans to the moon by 2018. Astronauts are expected to travel in a new spaceship that combines technologies developed for the space shuttle and Apollo programs.

The last lunar landing was during the Apollo 17 mission in 1972.

The new plan will cost about 104 billion U.S. dollars over the next 13 years and help President George W. Bush achieve the vision for space exploration that he outlined on January 14, 2004. At that time Bush said he wanted humans back on the moon by 2020.

On July 20, 1969, at 10:56 p.m. ET, Apollo 11 astronaut Neil Armstrong stepped off the “Eagle” onto the surface of the moon and said, “That’s one small step for man, one giant leap for mankind.”

Thirty-five years later, Steven Dick, NASA’s chief historian at the space agency’s headquarters in Washington, D.C., said that a thousand years from now, that step may be considered the crowning achievement of the 20th century.